Aetna CEO: Obamacare In A 'Death Spiral' Heading Into 2018. Aetna and Humana have called off their deal amid government concerns over competition. Here's a look back at six pivotal moments that led to this. Aetna and Humana have called off their deal amid government concerns over competition.
For the plant genus, see Synapsis (plant). Synapsis (also called syndesis) is the pairing of two homologous chromosomes that occurs during meiosis. It allows matching-up of homologous pairs prior to their segregation, and possible chromosomal crossover between them. Synapsis takes place during prophase I of meiosis.
Synapse. Neurons do not quite touch. The synapse (or synaptic cleft) is the small gap (about 20nm) between the pre-synaptic terminal button and the post-synaptic neuron (and, more closely, the pre-synaptic membrane and the post-synaptic membrane).Neurotransmitters cross this gap and either excite or inhibit the post-sypnaptic neuron.ynapse. Neurons do not quite touch. The synapse (or synaptic cleft) is the small gap (about 20nm) between the pre-synaptic terminal button and the post-synaptic neuron (and, more closely, the pre-synaptic membrane and the post-synaptic membrane).